Electrical fuse with metal line migration

ABSTRACT

An electrical fuse device is disclosed. A circuit apparatus can include the fuse device, a first circuit element and a second circuit element. The fuse includes a first contact that has a first electromigration resistance, a second contact that has a second electromigration resistance and a metal line, which is coupled to the first contact and to the second contact, that has a third electromigration resistance that is lower than the second electromigration resistance. The first circuit element is coupled to the first contact and the second circuit element coupled to the second contact. The fuse is configured to conduct a programming current from the first contact to the second contact through the metal line. Further, the programming current causes the metal line to electromigrate away from the second contact to electrically isolate the second circuit element from the first circuit element.

BACKGROUND

Technical Field

The present invention relates to electrical devices, and moreparticularly, to electrical fuses.

Description of the Related Art

During the development of semiconductor technology, fuses have beenincorporated in integrated circuits (ICs) to permit design flexibilityand to improve yield. For example, fuses can be employed to selectivelyde-activate portions of a generic integrated circuit (IC) and therebytailor the circuit to suit particular design needs. Further, fuses canalso be utilized in an IC fabricated with redundant elements to permitthe isolation and replacement of defective components of the circuit.Common fuse programming or “blow” techniques involve melting componentsof the fuse or severing components through the use of a laser. Inaddition, many fuses utilize geometric manipulation to implementprogramming. For example, dog-bone or dumb-bell shaped fuses effectprogramming through current density divergence, where current density ismaximized in a small cross-sectional area in the bridge of the device tosever the connection. However, current density divergence can be furtherleveraged with other more complex shapes, such as multi-tier fuses.

SUMMARY

One embodiment is directed to a circuit apparatus. The circuit apparatusincludes a fuse, a first circuit element and a second circuit element.The fuse includes a first contact that has a first electromigrationresistance, a second contact that has a second electromigrationresistance and a metal line, which is coupled to the first contact andto the second contact, that has a third electromigration resistance thatis lower than the second electromigration resistance. The first circuitelement is coupled to the first contact and the second circuit elementcoupled to the second contact. The fuse is configured to conduct aprogramming current from the first contact to the second contact throughthe metal line. Further, the programming current causes the metal lineto electromigrate away from the second contact to electrically isolatethe second circuit element from the first circuit element.

An alternative embodiment is directed to an electric fuse deviceincluding a first contact that has a first electromigration resistance,a second contact that has a second electromigration resistance and ametal line that has a third electromigration resistance that is lowerthan the second electromigration resistance. The metal line is coupledto the first contact and to the second contact. Further, the device isconfigured to conduct a programming current from the first contact tothe second contact through the metal line, where the programming currentcauses the metal line to electromigrate away from the second contact toprogram the device.

Another embodiment is directed to a method for programming an electricalfuse device. In accordance with the method, a cathode element is coupledto a contact that is connected to a metal line. In addition, an anodeelement is coupled to the metal line. Further, the anode and cathodeelements are activated to apply a programming current through thecontact and the metal line such that the metal line electromigrates awayfrom the contact as a result of the activation.

An alternative embodiment is directed to a method for fabricating a fusedevice. The method includes forming a first contact in a first apertureof an insulator and a second contact in a second aperture of theinsulator. In addition, a metal line is formed over the insulator, thefirst contact and the second contact. A cathode element is coupled tothe second contact and an anode element is coupled to the first contactsuch that activating the anode and cathode elements applies aprogramming current through the metal line such that the metal lineelectromigrates away from the second contact as a result of theactivation.

These and other features and advantages will become apparent from thefollowing detailed description of illustrative embodiments thereof,which is to be read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

The disclosure will provide details in the following description ofpreferred embodiments with reference to the following figures wherein:

FIGS. 1-2 are cross-sectional views of an electrical fuse device inaccordance with an embodiment of the present principles;

FIGS. 3-8 are cross-sectional views illustrating intermediate processingsteps for fabricating an electrical device in accordance with anembodiment of the present principles;

FIGS. 9-11 are cross-sectional views of a portion of a circuit apparatusincluding an electrical fuse device in accordance with an embodiment thepresent principles;

FIG. 12 is a block diagram of a portion of a circuit apparatus inaccordance with an embodiment of the present principles;

FIG. 13 is a block diagram of a portion of an alternative circuitapparatus in accordance with an embodiment of the present principles;

FIGS. 14-15 are cross-sectional views of an electrical fuse deviceillustrating a programming process in accordance with an embodiment ofthe present principles;

FIGS. 16-17 are cross-sectional views of a portion of a circuitapparatus illustrating a programming process in accordance with anembodiment of the present principles;

FIGS. 18-19 are cross-sectional views of a portion of a circuitapparatus illustrating a programming process in accordance with analternative embodiment of the present principles;

FIGS. 20-21 are cross-sectional views of a portion of a circuitapparatus illustrating a programming process in accordance with analternative embodiment of the present principles;

FIGS. 22-23 are cross-sectional views of a portion of a circuitapparatus illustrating a programming process in accordance with analternative embodiment of the present principles;

FIG. 24 is a flow diagram of a method for programming an electrical fusedevice in accordance with an embodiment of the present principles; and

FIG. 25 is a flow diagram of a method for fabricating an electrical fusedevice in accordance with an embodiment of the present principles.

DETAILED DESCRIPTION

In the embodiments described herein, fuses that have a substantiallyhigh degree of controllability and programming efficiency can befabricated and implemented in a simple and economical manner. Inparticular, complex geometrical manipulation need not be utilized toachieve controllability and programming efficiency benefits, asembodiments described herein need not rely on such current densitydivergence to effect programming of a fuse. For example, as described inmore detail herein below, contacts that have a higher electromigrationresistance than a metal line fuse element can be employed in a way thateffects migration of the metal line away from a contact to program thefuse. Specifically, these electromigration effects can be achievedwithout dependence of current density divergence provided by geometricmanipulation. Thus, fuse elements in accordance with the presentprinciples can be fabricated simultaneously with other circuit elementswithout the addition of processing steps, such as the application ofadditional photoresist masks or etching steps.

Moreover, the programming of fuse embodiments can be achieved withoutusing lasers or melting components of the fuse. As noted above,electromigration effects can be employed to migrate a metal line fuseelement from a contact of the fuse. The electromigration in accordancewith the present principles can be implemented using much less energythan melting and much better reproducibility, i.e. programming yield.Furthermore, as compared to melting, the electromigration of the metalline has a substantially lower chance of causing physical damage tosurrounding circuit elements.

As will be appreciated by one skilled in the art, aspects of the presentinvention may be embodied as a system, method, device or apparatus.Aspects of the present invention are described below with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems) and devices according to embodiments of the invention. Theflowchart and block diagrams in the Figures illustrate the architecture,functionality, and operation of possible implementations of systems,methods, devices and apparatuses according to various embodiments of thepresent invention. It should also be noted that, in some alternativeimplementations, the functions noted in the block may occur out of theorder noted in the figures. For example, two blocks shown in successionmay, in fact, be executed substantially concurrently, or the blocks maysometimes be executed in the reverse order, depending upon thefunctionality involved.

It is to be understood that the present invention will be described interms of a given illustrative architecture having a substrate; however,other architectures, structures, substrate materials and processfeatures and steps may be varied within the scope of the presentinvention.

It will also be understood that when an element described as a layer,region or substrate is referred to as being “on,” “above” or “over”another element, it can be directly on the other element or interveningelements may also be present. In contrast, when an element is referredto as being “directly on,” “directly above” or “directly over” anotherelement, there are no intervening elements present. Similarly, it willalso be understood that when an element described as a layer, region orsubstrate is referred to as being “beneath” or “below” another element,it can be directly beneath the other element or intervening elements mayalso be present. In contrast, when an element is referred to as being“directly beneath” or “directly below” another element, there are nointervening elements present. It will also be understood that when anelement is referred to as being “connected” or “coupled” to anotherelement, it can be directly connected or coupled to the other element orintervening elements may be present. In contrast, when an element isreferred to as being “directly connected” or “directly coupled” toanother element, there are no intervening elements present.

A design for an integrated circuit chip including fuse devices of thepresent principles may be created in a graphical computer programminglanguage, and stored in a computer storage medium (such as a disk, tape,physical hard drive, or virtual hard drive such as in a storage accessnetwork). If the designer does not fabricate chips or thephotolithographic masks used to fabricate chips, the designer maytransmit the resulting design by physical means (e.g., by providing acopy of the storage medium storing the design) or electronically (e.g.,through the Internet) to such entities, directly or indirectly. Thestored design is then converted into the appropriate format (e.g.,GDSII) for the fabrication of photolithographic masks, which typicallyinclude multiple copies of the chip design in question that are to beformed on a wafer. The photolithographic masks are utilized to defineareas of the wafer (and/or the layers thereon) to be etched or otherwiseprocessed.

Methods as described herein may be used in the fabrication of integratedcircuit chips. The resulting integrated circuit chips can be distributedby the fabricator in raw wafer form (that is, as a single wafer that hasmultiple unpackaged chips), as a bare die, or in a packaged form. In thelatter case, the chip is mounted in a single chip package (such as aplastic carrier, with leads that are affixed to a motherboard or otherhigher level carrier) or in a multichip package (such as a ceramiccarrier that has either or both surface interconnections or buriedinterconnections). In any case the chip is then integrated with otherchips, discrete circuit elements, and/or other signal processing devicesas part of either (a) an intermediate product, such as a motherboard, or(b) an end product. The end product can be any product that includesintegrated circuit chips, ranging from toys and other low-endapplications to advanced computer products having a display, a keyboardor other input device, and a central processor.

Referring now to the drawings in which like numerals represent the sameor similar elements and initially to FIGS. 1 and 2, an exemplary fusedevice 100 in accordance with one exemplary embodiment is illustrativelydepicted. FIG. 1 is a top-down view of the device, while FIG. 2 is aside view of the device along the B-B cross-section 103 of FIG. 1.Although the studs 104, 106 are not viewable from the top-down view ofthe fuse device 100, for illustrative purposes, the position of thestuds 104, 106 are shown in FIG. 1. The fuse device 100 includes a metalline 102, contacts 104 and 106, an insulator material 108 thatelectrically insulates contacts 104 and 106, an inter-layer dielectric(ILD) 112 and a dielectric cap layer 110. In accordance with oneexemplary embodiment, the metal line 102 is copper and the contacts 104,106 are tungsten. However, the materials for the metal line 102 and thecontacts 104, 106 can be chosen such that the electromigrationresistance of the metal line 102 is lower than the electromigrationresistance of the contacts 104, 106. As described in more detail hereinbelow, the fuse is configured such that the programming of the fuse canbe implemented by inducing electromigration of the metal line 102 from acontact. The contacts 106 and 104 can be coupled to different elementsof an integrated circuit, where the electrical connection to one of theelements can be severed through programming of the fuse to isolate thatelement from the rest of the circuit. In accordance with one exemplaryaspect, the studs 104-106 can have a height 120 of approximately 30-80nm and the distance between the two studs 122 (d) can be between 100-200nm. In addition, the cross-sectional area for the studs 104-106, in theview provided in FIG. 1, can be between about 900 nm² and about 25,000nm². Here, for tungsten contacts, the resistance of the contacts 104,106 is between 30-100 ohms with a current of about 4 mA and about 7 mA,which would induce programming of the fuse 100. The total resistance ofthe fuse element is controlled by the distance d 122, which in thisexample is between 10-20 ohms.

Prior to discussing the programming of the fuse 100 in detail,fabrication of the fuse is described for completeness purposes.Referring to FIGS. 3-8, with continuing reference to FIGS. 1 and 2, aninsulator 108 can be deposited on an area of a circuit, above asubstrate, on which the fuse 100 will be formed, as illustrated in FIG.3. For example, the insulator 108 can be silicon dioxide, or anyappropriate insulating oxide, and can be deposited using chemical vapordeposition. In addition, as shown in FIG. 4, appropriatephotolithography-involved patterning techniques and etching can beapplied to form apertures 402 and 404 in which the contacts 106 and 104will be formed, respectively. Further, a liner, not shown for brevitypurposes, such as titanium nitride, can be deposited in accordance withchemical-vapor deposition (CVD) or physical vapor deposition (PVD)techniques along the side walls 406, 408 of the apertures 402 and 404,respectively. As illustrated in FIG. 5, tungsten, or another suitablematerial, can be deposited in accordance with, for example, CVDtechniques, in the apertures 402 and 404 to form contacts 106 and 104,respectively. In addition, the top surface 502 of the resultingstructure can be planarized using, for example, chemical-mechanicalplanarization techniques. Additionally, as shown in FIG. 6, a dielectriccap layer 110, which can be silicon nitride, or another suitabledielectric, can be deposited over the surface 502. As provided in FIG.7, an inter-layer dielectric material 112 can be deposited on thedielectric cap 110. The dielectric material 112 can be used to isolatethe fuse 110 from other fuses and/or other components of an integratedcircuit. Photolithographic patterning and etching techniques can beemployed, as illustrated in FIG. 8, to form a region 802 in which themetal line 102 can be formed. For example, tantalum nitride liner, notshown for purposes of brevity, can be deposited on the side walls of theaperture 802 in accordance with, for example, PVD techniques. Moreover,electroplating techniques can be employed to form the metal line 102, asillustrated in FIG. 2. Further, chemical mechanical planarization can beapplied to the top surface of the resulting structure to ensure propercoupling to any other circuit elements. For example, as described inmore detail below, the metal line 102 can be coupled through a via toanother layer of a circuit.

FIGS. 9-11 provide different views of an implementation in which thee-fuse 100 is co-fabricated simultaneously with other components of acircuit. For example, FIG. 9 shows a top-down view of a portion 901 of acircuit including the fuse element 100 and two interconnects 900 and920. The interconnect 900 is composed of a metal line and theinterconnect 920 is composed of a metal line 924 and a contact 922. Themetal lines 900 and 924 can also be composed of suitable metals, such ascopper. Although the contacts 104, 106 and 922 are not viewable from thetop-down view of the fuse device 100, for illustrative purposes, theposition of the contacts are shown in FIG. 9. FIG. 10 provides a sideview of the portion 901 along the A-A cross-section 952 of FIG. 9, whileFIG. 11 provides a side view of the portion 901 along the B-Bcross-section 950 of FIG. 9.

As indicated above, the e-fuse 100 can be used as a means to isolate oneor more components of a circuit upon programming. FIGS. 12 and 13illustrate how the e-fuse can be implemented in a cell design system1201 and an array design system 1301, respectively. For example, asdepicted in FIG. 12, the e-fuse 100 can be employed to electricallycouple a circuit component 1250 with a cell 1200, which can include aplurality of field-effect transistors, as illustrated by contacts 1202to which connections can be made thereto. As shown in FIG. 13, thee-fuse can also be incorporated in an array design. For example, e-fuses100 a and 100 b can couple cells 1356 and 1358 to component 1302, whilee-fuses 100 c and 100 d can couple cells 1352 and 1354 to component1304. Similar to FIG. 12, each cell 1352-1358 can include a plurality offield-effect transistors, as illustrated by contacts 1351 to whichconnections can be made thereto. It should be noted that the contacts104 a-d and 106 a-d of the e-fuses 100 a-d can have a differentcross-sectional contact area than the contacts 1202 and 1351. Thee-fuses 100, 100 a-d can be programmed as described herein below torespectively isolate cells 1200, 1356, 1358, 1352 and 1354 from the restof their respective integrated circuits.

Turning now to FIGS. 14 and 15, block diagrams of the e-fuse 100illustrating how the fuse can be programmed in accordance with oneimplementation are provided. FIG. 14 depicts a top-down view of thefuse-element 100, similar to FIG. 1, while FIG. 15 depicts a side viewof the fuse element 100 along the B-B cross-section 1402 of FIG. 14.Here, to program the e-fuse 100, the contacts 104 and 106 arerespectively coupled to a cathode and anode of a pre-determinedprogramming potential to generate a programming current that flows fromthe contact 106 to the contact 104 through the metal line 102. As notedabove, the contacts 104 and 106 can be tungsten while the metal line 102can be copper. In particular, the contacts 104 and 106 can have anelectromigration resistance that is higher than the metal line 102. Uponapplication of the programming current to the e-fuse 100, electrons areforced into the metal line 102 through the contacts 104 and 106, therebycausing electromigration of the metal line 102 away from the contact 104(cathode) towards the anode 106 to create a physical void between themetal line 102 and the contact 104 and break the electrical connectionof the fuse. The difference of electromigration resistance between thecontacts and the metal line ensures that programming occurs at thecontact-metal line interface 1502. Thus, in one embodiment in which themetal line 102 is copper and the contacts 104 and 106 are tungsten,copper atoms are migrated away from the contact 104 upon application ofthe programming current. As noted above, if the resistance of thetungsten contacts 104, 106 is between about 30 ohms and about 100 ohms,a programming current of about 4 mA and about 7 mA would induceprogramming of the fuse 100.

In contrast to fuses that rely on geometric manipulation, there is noelectron current diversion in the fuse element embodiment 100.Furthermore, also contrary to fuses that incorporate geometricmanipulation, additional lithography masking and etching steps need notbe added to the circuit fabrication process. As such, because the e-fuse100 need not rely on current density divergence, the formation of thefuse in integrated circuits that are increasingly fabricated on smallerscales is substantially facilitated. Moreover, the programming of thefuse 100 need not involve melting of any components. Thus, theprogramming described herein utilizes less energy, reduces thelikelihood of physical damage to nearby circuit elements and, as aresult, is more reliable and provides a fuse with a longer service lifethan fuses that rely on melting for programming.

In addition, the configuration of the fuse and the programming processprovides further advantages for fuses that incorporate contacts thathave a higher electromigration resistance than the metal line. Forexample, referring again to the tungsten contacts and copper lineexample, an alternative configuration may use the tungsten contact asthe fuse element by situating the cathode at the metal line and theanode below the contact. However, tungsten is a very heavy metal anduses an excessive amount of energy for migration. Further, the migrationof the tungsten in this alternative configuration has a relatively lowconsistency. In contrast, the programming described here with respect toFIGS. 14 and 15 uses the copper line as the fuse element and exploitsthe electromigration resistivity difference to migrate the copper thatis in contact with tungsten and thereby create an electricaldiscontinuity with less energy and greater consistency.

In accordance with other advantageous aspects, optional local heating ofthe metal line by the contacts 102 and 104 can accelerate theprogramming process by providing a migration-enhancing thermalenvironment for the metal line. The optional additional assist heatingis described in more detail herein below with respect to more detailedembodiments of the present principles.

Referring now to FIGS. 16-24, alternative fuse embodiments andprogramming processes are described. FIGS. 16-17 effectively illustratethe same embodiment described above with respect to FIGS. 14 and 15.FIG. 16 depicts a top-down view of the fuse-element 100, similar to FIG.1, while FIG. 17 depicts a side view of the fuse element 100 along theB-B cross-section 1402 of FIG. 16. Here, both the interconnects for fuse100 and element 920 are M1 interconnects and the programming isimplemented as described above with respect to FIGS. 14 and 15. Forexample, the cathode is disposed at contact 104 and the anode isdisposed at the contact 106. As the programming current 1704 is appliedbetween the contact 106 and contact 104 through the metal line 102, themetal atoms of the metal line 102 migrate away from the interface 1502between the contact 104 and the metal line 102 to thereby sever theelectrical connection to the contact 104. Arrow 1702 illustrates thedirection of the programming current, while arrow 1704 illustrates theflow of the programming current between the contacts 106 and 104 throughthe metal line 102.

FIGS. 18-19 illustrate a fuse in which the programming is similar tothat of FIGS. 16 and 17, but the configuration of the interconnects aredifferent. FIG. 18 depicts a top-down view of the fuse-element 1800 andinterconnect 1850 at a planar cross section that is at the top of themetal line 102, similar to FIG. 1, while FIG. 19 depicts a side view ofthe fuse element 1800 along the B-B cross-section 1852 of FIG. 18. Here,the fuse 1800 and the interconnect 1850 are M1 interconnects that arecoupled to M2 elements through respective vias 1802 and 1851. Similar tothe programming described with respect to FIGS. 14 and 15, the cathodeis disposed at the contact 104 and the anode is disposed at the contact106. As the programming current is applied between the contact 106 andthe contact 104 through the metal line 102, the metal atoms of the metalline 102 migrate away from the interface 1502 to sever the electricalconnection to the contact 104. Arrow 1902 illustrates the direction ofthe current flow in the fuse 1800, while arrow 1704 illustrates the flowof the programming current between the contacts 106 and 104 through themetal line 102. Thus, any circuit elements coupled to the fuse 1800through the contact 104 are electrically isolated from any circuitelements coupled to the fuse through contact 106 and the via 1802 as aresult of the programming.

The fuse elements depicted in FIGS. 20-21 and FIGS. 22-23 areessentially the same as the fuse elements depicting in FIGS. 16-17 andFIGS. 18-19, respectively, except for the programming currents applied.In the embodiment illustrated in FIG. 21, an additional programmingcurrent 2102 is applied such that an anode is disposed at end 2104 ofthe fuse 100 and a cathode is disposed at end 2106 of the fuse 100.Similarly, in the embodiment illustrated in FIG. 23, an additionalprogramming current 2302 is applied such that an anode is disposed atend 2104 of the fuse 1800 and a cathode is disposed at the via 1802 ofthe fuse 1800. In both of the cases depicted in FIGS. 20-21 and FIGS.22-23, a programming current 2204 is maintained between contact 106 andcontact 104 through the metal line 102, as described above with respectto FIGS. 16-17 and FIGS. 18-19. However, here, the combination of theadditional programming current 2102, 2302 and the programming currentbetween the contacts 106 and 104 result in electromigration of the metalline from the contact 104, as described above, and anelectromigration-enhancing temperature due to heating from the closelysituated contacts. The resultant heating provides an environment that ismore conducive to electromigration of the metal line 102, therebyimproving the consistency and efficiency of the programming of the fuses100 and 1800.

Referring now to FIG. 24, with continuing reference to FIGS. 1-23, amethod 2400 for programming an electrical fuse device in accordance withone illustrative embodiment is depicted. It should be noted that themethod can be applied to any of the fuse device embodiments describedabove and in any of the circuit environments described above. The method2400 can begin at step 2402, at which a cathode element can be coupledto a first contact that is connected to a metal line. For example, asdescribed above with respect to FIGS. 15-23. A cathode element can becoupled to the contact 104. Here, an external pad can be coupled to thecontact 104 to act as the cathode in the programming of the fuse. Inaddition, a circuit element can be coupled to the contact 104. Forexample, as noted above with respect to FIGS. 12 and 13, the contact 104can be coupled to circuit elements 1200, 1356, 1358, 1352 or 1354.

At step 2404, an anode element can be coupled to a second contact. Forexample, as described above with respect to FIGS. 15-23, an anodeelement can be coupled to the contact 106, which in turn is coupled tothe metal line 102. Similar to the cathode element example describedabove, an external pad can be coupled to the contact 106 to act as theanode in the programming of the fuse. Further, a different circuitelement can be coupled to the contact 106. For example, as noted abovewith respect to FIGS. 12 and 13, the contact 106 can be coupled tocircuit elements 1250, 1302 or 1304.

Optionally, at step 2406, a second cathode element and a second anodeelement can be coupled to a metal line of the fuse element. For example,as described above with respect to FIGS. 21 and 23, an anode element canbe coupled to end 2104 of the metal line 102, while a cathode elementcan be coupled to end 2106 of the metal line 102 as described above withrespect to FIG. 21. In addition, as discussed above with respect to FIG.23, the cathode element can also be coupled to the via 1802, which isconnected to a separate level of the circuit apparatus.

At step 2408, the cathode and anode elements, and optionally, the secondcathode and anode elements, can be activated to program the electricalfuse device. For example, a predetermined voltage can be applied to theexternal pads coupled to the contacts 106 and 104 at step 2404.Optionally, a predetermined voltage can be applied to the external padscoupled to the metal line at step 2406. The activation of the cathodeand anode can cause the fuse device to conduct a programming currentfrom the contact 106 to the contact 104 through the metal line 102.Further, the programming current can cause the metal line toelectromigrate away from the contact 104. The programming of the fusedevice in this way can electrically isolate the circuit element coupledto the contact 104 from the other circuit elements. For example, theprogramming of the fuse device can electrically isolate the circuitelement coupled to the contact 104 from the circuit element coupled tothe contact 106. In the configuration illustrated in FIG. 12, theprogramming of the fuse 100 can electrically isolate the element 1200from the element 1250. Similarly, in the configuration illustrated inFIG. 13, the programming of the fuse 100 a can electrically isolate theelement 1356 from the element 1302. Moreover, as noted above, if theoptional second cathode and anode elements are activated across themetal line 102, a second programming current conducts through the metalline. For example, as noted above with respect to FIGS. 21 and 23,second programming currents 2102 and 2302 can be applied across themetal line 102. Here, as described above with respect to FIGS. 21 and23, the first programming current 2204 can heat the metal line 102 toaid the electromigration of the metal line 102. For example, in the casein which a copper line is used, the metal line can be heated to atemperature of 40-350° C. As also stated above with respect to FIG. 23,the metal line 102 can be coupled to a via 1802 such that the secondprogramming current flows through the via to a circuit element on aseparate level of the circuit apparatus. In this case, theelectromigration of the metal line 102 away from the contact 104isolates the circuit element coupled to the contact 104 from theseparate level of the circuit apparatus.

Referring now to FIG. 25, with continuing reference to FIGS. 1-24, amethod 2500 for fabricating a fuse device in accordance with anexemplary embodiment is illustrated. It should be understood that themethod 2500 can be employed to fabricate any one or more of the fusedevices described above. In addition, the programming method 2400 can beapplied to a fuse device fabricated in accordance with the method 2500.The method 2500 can begin at step 2502, at which contacts can be formedin an insulator 2502. For example, as described above with respect toFIGS. 3-6, an insulator 108 can be provided and apertures 402 and 404can be etched. Further, contacts 106 and 104 can be formed within theapertures 402 and 404. As noted above, the contacts 106 and 104 can betungsten contacts.

At step 2504, a metal line can be formed over the contacts and theinsulator. For example, as described above with respect to FIGS. 2 and5-8, a cap layer 110 and an interlayer dielectric 112 can be formed overthe contacts 106 and 104 and the insulator 108. In addition, the layers110 and 112 can be etched and the metal line 102 can be formed in region802. The metal line can be connected to other components of a circuit.For example, the metal line can be an integral part of a circuit that isconnected to a variety of different elements. As described above, themetal line 102 can be a material that has a lower electromigrationresistance than the contacts 106 and 104. For example, if the contacts106 and 104 are tungsten contacts, then the metal line can be a copperline. Moreover, the thickness of the metal line between the first andsecond contacts, from any cross-sectional viewing angle, is constant.For example, as illustrated in FIGS. 14 and 15, the thickness of themetal line 102 is constant in both the top view and the side view of thefuse. In contrast, as described above, fuses that rely on geometricmanipulations to create a current density divergence will not have afuse element that has a consistent thickness, from any viewing angle,between an anode and a cathode.

Optionally, at step 2506, a via can be formed over the metal line. Forexample, as illustrated in FIGS. 19 and 23, a via 1802 can be formeddirectly over the metal line 102 to couple the metal line to one or morecircuit elements to a separate level of a circuit.

At step 2508, a cathode element and an anode element can be coupled tothe contacts. For example, the cathode element and the anode element canbe coupled to the contacts as described above with respect to steps 2402and 2404 of the method 2400. For example, the coupling can be made suchthat activating the anode and cathode elements applies a programmingcurrent through the metal line to induce the metal line toelectromigrate away from the first contact as a result of theactivation. Optionally, at step 2510, a second cathode element and asecond anode element can be coupled to the metal line. For example, thesecond cathode and the second anode elements can be coupled to the metalline as described above with respect to step 2406 of the method 2400.For example, the coupling can be made such that activation of the secondcathode element and the second anode element applies a secondprogramming current through the metal line. As indicated above, theprogramming current applied through the metal line 102 between thecontact 106 and the contact 104 can heat the metal line to aid theelectromigration of the metal line. Further, if the via is formed atstep 2506, the second cathode element can be coupled to the metal line102 through the via such that the second programming current flowsthrough the via to a separate level of the circuit in which the fuse isfabricated. It should be noted that steps 2508 and 2510 can berespectively implemented as steps 2402-2404 and 2406 of the method 2400if both of the methods 2500 and 2400 are performed.

Having described preferred embodiments of systems, apparatuses anddevices including an electrical fuse with metal line migration andmethods of fabrication and programming (which are intended to beillustrative and not limiting), it is noted that modifications andvariations can be made by persons skilled in the art in light of theabove teachings. It is therefore to be understood that changes may bemade in the particular embodiments disclosed which are within the scopeof the invention as outlined by the appended claims. Having thusdescribed aspects of the invention, with the details and particularityrequired by the patent laws, what is claimed and desired protected byLetters Patent is set forth in the appended claims.

What is claimed is:
 1. A method for programming an electrical fusedevice comprising: coupling a cathode element comprising tungsten to acontact that is connected to a metal line comprised of copper; couplingan anode element comprising tungsten to the metal line; and activatingthe anode and cathode elements to apply a programming current rangingfrom 4 mA to 7 mA through the contact and the metal line such that themetal line electromigrates away from the contact forming anelectromigration opening portion of the electrical fuse present in themetal line underlying one of the cathode element and the anode element,wherein each of said cathode element and said anode element have aheight ranging from 30 nm to 80 nm.
 2. The method of claim 1, wherein adistance between said anode element and said cathode element ranges from100 nm to 200 nm.
 3. The method of claim 2, wherein the contact is afirst contact, wherein the coupling the anode element further comprisescoupling the anode element to a second contact such that the activatingcauses the programming current to flow between the second contact andthe first contact through the metal line.
 4. The method of claim 3,wherein the programming current is a first programming current andwherein the method further comprises: coupling a second cathode elementand a second anode element to the metal line, wherein the activatingcomprises activating the second cathode element and the second anodeelement to apply a second programming current through the metal line,wherein the first programming current heats the metal line to aid theelectromigration of the metal line.
 5. The method of claim 4, whereinthe coupling the second cathode element further comprises coupling thesecond cathode element to the metal line through a via connected to aseparate level of a circuit and wherein the second programming currentflows to the separate level through the via.
 6. The method of claim 3,wherein a thickness of the metal line between the first and secondcontacts, from any cross-sectional viewing angle, is constant.